Introduction to pharmaceutics PHM224Y/PHC330Y Gregory Poon, PhD, BScPhm, RPh

Course organization PHM224Y PHC330Y (S. Wu) PHM224Y (G. Poon) PHC330Y (S. Wu) Fall term 2005 Winter term 2006

Contact information Gregory Poon, PhD, BScPhm, RPh Ontario Cancer Institute Princess Margaret Hospital MSN Your friendly TAs Gamal Rayan Jim Moselhy Tony Liu

What is pharmaceutics? The art and applied science of dosage form design The interface between drug and body A broad field that draws from many disciplines Physical chemistry (organic and inorganic) Medicinal chemistry Anatomy, physiology Microbiology Atomic physics Engineering (chemical, material) Deals with many aspects of interactions both inside and outside the body It’s not trivial to design and implement a dosage form that is both safe and effective for the drug’s intended use!

Pharmaceutics is unique to pharmacy Physicians and other prescribers don’t learn and apply physical pharmaceutical principles Chemists and engineers don’t learn a whole lot of biology Anyone can read the latest review article of a disease state and play armchair prescriber, but it takes a pharmacist to know how to deliver a drug safely and effectively!

PHARMACODYNAMICS Site/mechanism of action, potency, efficacy, etc. PHARMACOKINETICS absorption, distribution, metabolism, excretion

Logistical considerations of dosage form design Storage Rate of degradation (expiry) Liquid/solid? What conditions? Temperature Humidity What container How inert is it? What is the risk for contamination? Compatibility Active vs. active vs. “inert” ingredients Container (again) Organoleptic considerations Physical appearance, taste, smell, tactility, size “Pharmaceutical elegance” Manufacturing For a powder, how well does it flow?

What you must know to design a dosage form Physicochemical properties of the drug Reactivity, stability Solubility, acid/base, solid state behaviour Biopharmaceutical considerations What is the intended site of action? Systemic? Topical? Where/how well is the drug absorbed? What is the intended onset of action? Immediate-release, sustained-release, pulse releases

Example: estrogen Indication: hormone replacement therapy for treatment of symptoms of menopause Molecule administered is Conjugated estrogens Estradiol Estrone Dosage forms Tablets (Estrace®) Transdermal patch (Estraderm®, etc.) Transdermal gel (EstroGel®) Vaginal ring (Estring®)

Some questions and issues About the drug Aqueous solubility, pKa, partition coefficient Chemical stability in solution About the dosage form Dissolution characteristics Transdermal characteristics Stability in storage About the biopharmaceutics Extent of absorption First-pass metabolism Intended use: topical vs. systemic?

Each dosage form caters to a different need Compressed tablet Contains micronized estradiol Micronization improves dissolution 1 to 2 mg/day po Estradiol is highly metabolized Transdermal Bypasses first-pass metabolism Patch: 0.05 to 0.1 mg/day, applied twice weekly Gel: 0.75 mg/day Vaginal ring Topical application of estradiol for local symptoms Average 7.5 µg/day  90 days

A list of dosage forms Solid dosage forms Powders Tablets Capsules (hard, soft) Suppositories* Ointment, cream, gel, etc.* Aerosol Lozenge Cigarette Liquid dosage forms Solutions Suspensions (Gas) Light UV  rays Many administration routes Oral Parenteral IV, IM, SC, etc. Ophthalmic, otic Nasal Rectal, vaginal, urethral Buccal Topical